Expression of EphA2 and E-cadherin in gastric cancer: correlated with tumor progression and lymphogenous metastasis

Role of CDH1 gene variants and E-cadherin localization in gastric mucosal cancerization

Background

This study investigates the role of CDH1 gene single nucleotide polymorphisms (SNPs), mRNA transcription levels, and E-cadherin protein localization in Helicobacter pylori (Hp)-associated gastric diseases and their contribution to gastric mucosal carcinogenesis.

Methods

Gastric mucosal samples were analyzed for histopathology (Hematoxylin-Eosin staining) and Hp detection (rapid urease test, Giemsa staining). SNPs at the CDH1 gene rs16260 locus were identified via sequencing, mRNA levels were quantified by real-time PCR, and E-cadherin localization was assessed using Elivision™ Plus. Statistical analyses were performed with SPSS 25.0.

Results

Participants were grouped by gastric mucosal pathology: normal (NOR), gastric inflammation (GI), gastric atrophy (GA), gastric premalignant lesion (GPL), severe dysplasia (GSD), and gastric cancer (GC). No significant differences were found in CDH1 rs16260 genotypes. However, CDH1 transcription was higher in GC compared to NOR and GPL groups. Intestinal metaplasia showed lower CDH1 mRNA levels. E-cadherin expression was higher in GSD and GC compared to other groups. Localization analysis revealed decreased membrane-bound E-cadherin with increased cytoplasmic expression as lesion severity increased. Quantitative analysis showed higher E-cadherin expression in GA than other groups, indicating an initial rise followed by a decline in malignancy. Regression analysis suggested that elevated CDH1 mRNA increased gastric cancer risk, while E-cadherin cytoplasmic ectopic expression heightened the risk of precancerous lesions and gastric cancer.

Conclusion

The A allele of the CDH1 gene rs16260 locus show no effect in gastric mucosal pathological evolution, while the elevated mRNA transcription levels potentially increasing the risk of gastric cancer. The loss and ectopic expression of E-cadherin may be significant risk factors for malignant transformation in the gastric mucosa.

Advances and current concepts on Eph receptors and ephrins in upper digestive tract cancers

Erythropoietin-producing hepatocellular (Eph) receptors comprise the largest group of surface receptors and are responsible for cellular signals. Eph/ephrin signaling has been identified to play a role in key cancer development and progression processes, especially in the upper gastrointestinal tract. The Eph/ephrin system has been described as a tumor suppressor in duodenal cancer, while in esophageal, gastric, hepatic, and pancreatic cancer, the system has been related to tumor progression. For their significant role in developing a wide range of malignancies, Eph receptors and their ligands have proven to be an important target for new anticancer therapies. In this review, we present an overview of the literature and highlight evidence supporting the role of the Eph/ephrin system in upper digestive tract cancers. In addition, we discuss molecular findings that represent promising therapeutic targets for these cancers.

Erythropoietin-induced hepatocyte receptor A2 regulates effect of pyroptosis on gastrointestinal colorectal cancer occurrence and metastasis resistance

Erythropoietin-induced hepatocyte receptor A2 (EphA2) is a receptor tyrosine kinase that plays a key role in the development and progression of a variety of tumors. This article reviews the expression of EphA2 in gastrointestinal (GI) colorectal cancer (CRC) and its regulation of pyroptosis. Pyroptosis is a form of programmed cell death that plays an important role in tumor suppression. Studies have shown that EphA2 regulates pyrodeath through various signaling pathways, affecting the occurrence, development and metastasis of GI CRC. The overexpression of EphA2 is closely related to the aggressiveness and metastasis of GI CRC, and the inhibition of EphA2 can induce pyrodeath and improve the sensitivity of cancer cells to treatment. In addition, EphA2 regulates intercellular communication and the microenvironment through interactions with other cytokines and receptors, further influencing cancer progression. The role of EphA2 in GI CRC and its underlying mechanisms provide us with new perspectives and potential therapeutic targets, which have important implications for future cancer treatment.

EPHA2, EPHA4, and EPHA7 Expression in Triple-Negative Breast Cancer

Ongoing research continues to elucidate the complex role of ephrin receptors (EPHs) and their ligands (ephrins) in breast cancer pathogenesis, with their varying expression patterns implied to have an important impact on patients’ outcome. The current study aims to investigate the clinical significance of EPHA2, EPHA4, and EPHA7 expression in triple-negative breast cancer (TNBC) cases. EPHA2, EPHA4, and EPHA7 protein expression was assessed immunohistochemically on formalin-fixed and paraffin-embedded (FFPE) TNBC tissue sections from 52 TNBC patients and correlated with key clinicopathologic parameters and patients’ survival data (overall survival (OS); disease-free survival (DFS)). EPHA2, EPHA4, and EPHA7 expression was further examined in TNBC cell lines. EPHA2 overexpression was observed in 26 (50%) of the TNBC cases, who exhibited a shorter OS and DFS than their low-expression counterparts, with EPHA2 representing an independent prognostic factor for OS and DFS (p = 0.0041 and p = 0.0232, respectively). EPHA4 overexpression was associated with lymph node metastasis in TNBC patients (p = 0.0546). Alterations in EPHA2, EPHA4, and EPHA7 expression levels were also noted in the examined TNBC cell lines. Our study stresses that EPHA2 expression constitutes a potential prognostic factor for TNBC patients. Given the limited treatment options and poorer outcome that accompany the TNBC subtype, EPHA2 could also pose as a target for novel, more personalized, and effective therapeutic approaches for those patients.

Emerging therapeutic targets for gastric cancer from a host-Helicobacter pylori interaction perspective

INTRODUCTION

Gastric cancer (GC) has the higher genetic, cytologic, and architectural heterogeneity compared to other gastrointestinal cancers. By inducing gastric inflammation, Helicobacter pylori (HP) may lead to GC through combining bacterial factors with host factors. In this regard, identification of the major therapeutic targets against the host-HP interactions plays a critical role in GC prevention, diagnosis, and treatment.

AREAS COVERED

This study offers new insights into the promising therapeutic targets against the angiogenesis, invasion, or metastasis of GC from a host-HP interaction perspective. To this end, MEDLINE, EMBASE, LILACS, AIM, and IndMed databases were searched for relevant articles since 1992.

EXPERT OPINION

Wnt signaling and COX pathway have a well-documented history in the genesis of GC by HP and might be considered as the most promising targets for early GC treatment. Destroying HP may decrease the risk of GC, but it cannot fully hinder the GC development induced by HP infection. Therefore, targeting HP-activated pathways, especially COX-2/Wnt/beta-catenin/VEGF, TLR2/TLR9/COX-2, COX2-PGE2, and NF-κB/COX-2, as well as EPHA2, MMPs, and miR-543/SIRT1 axis, can be an effective measure in the early treatment of GC. However, different clinical trials and large, multi-center cohorts are required to validate these potentially effective targets for GC therapy.

Ephrin-A2 promotes prostate cancer metastasis by enhancing angiogenesis and promoting EMT

BACKGROUND

Ephrin-A2, a member of the Eph receptor subgroup, is used in diagnosing and determining the prognosis of prostate cancer. However, the role of ephrin-A2 in prostate cancer is remains elusive.

METHODS

We established stable clones overexpressing or silencing ephrin-A2 from prostate cancer cells. Then, CCK-8 was used in analyzing the proliferation ability of cells. CD31 staining was used in evaluating angiogenesis. Migration and invasion assay were conducted in vivo and in vitro. The expression of EMT-related markers was evaluated in prostate cancer cells through Western blotting.

RESULTS

We revealed that the ectopic expression of ephrin-A2 in prostate cancer cells facilitated cell migration and invasion in vitro and promoted tumor metastasis and angiogenesis in vivo and that the silencing of ephrin-A2 completely reversed this effect. Although ephrin-A2 did not affect tumor cell proliferation in vitro, ephrin-A2 significantly promoted primary tumor growth in vivo. Furthermore, to determine the biological function of ephrin-A2, we assayed the expression of EMT-related markers in stable-established cell lines. Results showed that the overexpression of ephrin-A2 in prostate cancer cells down-regulated the expression of epithelial markers (ZO-1, E-cadherin, and claudin-1) and up-regulated the expression of mesenchymal markers (N-cadherin, β-catenin, vimentin, Slug, and Snail), but the knocking out of ephrin-A2 opposed the effects on the expression of EMT markers.

CONCLUSIONS

These findings indicate that ephrin-A2 promotes prostate cancer metastasis by enhancing angiogenesis and promoting EMT and may be a potentially therapeutic target in metastatic prostate cancer.

Helicobacter Pylori Targets the EPHA2 Receptor Tyrosine Kinase in Gastric Cells Modulating Key Cellular Functions

Helicobacter pylori, a stomach-colonizing Gram-negative bacterium, is the main etiological factor of various gastroduodenal diseases, including gastric adenocarcinoma. By establishing a life-long infection of the gastric mucosa, H. pylori continuously activates host-signaling pathways, in particular those associated with receptor tyrosine kinases. Using two different gastric epithelial cell lines, we show that H. pylori targets the receptor tyrosine kinase EPHA2. For long periods of time post-infection, H. pylori induces EPHA2 protein downregulation without affecting its mRNA levels, an effect preceded by receptor activation via phosphorylation. EPHA2 receptor downregulation occurs via the lysosomal degradation pathway and is independent of the H.pylori virulence factors CagA, VacA, and T4SS. Using small interfering RNA, we show that EPHA2 knockdown affects cell–cell and cell–matrix adhesion, invasion, and angiogenesis, which are critical cellular processes in early gastric lesions and carcinogenesis mediated by the bacteria. This work contributes to the unraveling of the underlying mechanisms of H. pylori–host interactions and associated diseases. Additionally, it raises awareness for potential interference between H. pylori infection and the efficacy of gastric cancer therapies targeting receptors tyrosine kinases, given that infection affects the steady-state levels and dynamics of some receptor tyrosine kinases (RTKs) and their signaling pathways.

Role of EphA2-PI3K signaling in vasculogenic mimicry induced by cancer-associated fibroblasts in gastric cancer cells

Although erythropoietin-producing human hepatocellular receptor A2 (EphA2) signaling serves an important role in the tumor microenvironment, its contribution to vasculogenic mimicry (VM) formation in gastric cancer cells remains unclear. The aim of the present study was to investigate the role of EphA2 in VM formation induced by cancer-associated fibroblasts (CAFs). The conditioned medium of CAFs (CAF-CM) was prepared from 12 patients with gastric adenocarcinoma. VM was evaluated by the number of tubules and intersections in gastric cancer cells following CAF-CM treatment. The role of EphA2-phosphoinositide 3-kinase (PI3K) in VM was investigated using EphA2-targeted small interfering (si)RNAs (siEphA2), EphA2 inhibitors and PI3K-inhibitors. CAF-CM-induced VM formation was significantly associated with high protein expression levels of EphA2. EphA2 inhibitor and siEphA2 manipulation significantly decreased VM formation by CAF-CM. In siEphA2 cells, decreased expression levels of VM-associated proteins were observed. CAF-CM-induced VM formation was blocked by the PI3K-inhibitor. In conclusion, CAFs facilitate VM formation via EphA2-PI3K signaling in gastric cancer cells. Thus, EphA2-PI3K signaling may be required for CAF-promoted VM formation during gastric tumorigenesis.

Silencing of EPHB2 promotes the epithelial-mesenchymal transition of skin squamous cell carcinoma-derived A431 cells

Erythropoietin-producing hepatocellular (Eph) receptors and their ligand ephrins serve crucial roles in the interactions among epithelial cells. Eph receptor/ephrin signaling regulates cell functions, including proliferation, differentiation and migration, via these cell-cell interactions. We reported previously that EPHB2, a member of the Eph receptor family, was highly expressed in chemically induced cutaneous squamous cell carcinoma (cSCC) tissues in mice. Although the higher expression level of EPHB2 has been observed in various human cancers, its roles in the development and progression of cancers are still unclear. In the present study, the functional implications of EPHB2 in the acquisition of malignant phenotypes of cSCC cells was investigated. Silencing of EPHB2 in the human cSCC cell line A431 induced epithelial-mesenchymal transition (EMT)-like morphological changes accompanied by a significant upregulation of epithelial-mesenchymal transition-associated genes such as zinc finger E-box binding homeobox 1/2. In addition, silencing of EPHB2 suppressed anchorage-independent cell growth under 3D culture conditions. Consistent with these observations, EPHB2 exhibited higher levels of expression in tumor spheres formed under 3D culture conditions than in cells cultured in adherent form, and the expression pattern of EMT markers indicated that EMT was suppressed in tumor spheres. The results of the present study indicated that EPHB2 serves a pivotal role in promoting the anchorage-independent growth of A431 cells through the suppression of EMT.

Cancer-associated fibroblasts promote gastric tumorigenesis through EphA2 activation in a ligand-independent manner

PURPOSE

Under physiologic conditions, the binding of erythropoietin-producing hepatocellular (Eph) A2 receptor and its ligand ephrinA1 results in decreased EphA2 level and tumor suppression. However, EphA2 and ephrinA1 are highly expressed in human cancers including gastric adenocarcinoma. In this study, we tested our hypothesis that cancer-associated fibroblasts (CAFs) promote gastric tumorigenesis through EphA2 signaling in a ligand-independent manner.

METHODS

Expression of EphA2 protein in primary tumor tissues of 91 patients who underwent curative surgery for gastric adenocarcinoma was evaluated by immunohistochemistry and western blotting. Conditioned medium of cancer-associated fibroblasts (CAF-CM) was used to evaluate the tumorigenic effect of CAFs on gastric cancer cell lines. Epithelial-mesenchymal transition (EMT), cell proliferation, migration, and invasion were assessed. EphrinA1-Fc ligand was used to determine the suppressor role of EphA2 receptor-ligand binding.

RESULTS

CAF-CM-induced EMT and promoted cancer cell motility even without cell-cell interaction. Treatment with a selective EphA2 inhibitor (ALW-II-41-27) or EphA2-targeted siRNA markedly reduced CAF-CM-induced gastric tumorigenesis. EphrinA1-Fc ligand treatment showing ligand-dependent tumor suppression diminished the EphA2 expression and EMT progression. In contrast, ephrinA1-targeted siRNA did not significantly affect CAF-CM-mediated increases in EphA2 expression and EMT progression. Treatment with VEGF showed effects like CAF-CM in terms of EphA2 activation and EMT progression.

CONCLUSION

CAFs may contribute to gastric tumorigenesis by activating EphA2 signaling pathway in a ligand-independent manner. Our results suggest that ligand-independent activation of EphA2 was triggered by VEGF released from CAF-CM. Our result may partially explain why ligand-dependent tumor suppressor roles of EphA2 are not evident in gastric cancer despite the prominent level of ephrinA1.

SSX2 regulates focal adhesion but does not drive the epithelial to mesenchymal transition in prostate cancer

Prostate cancer is the most commonly diagnosed malignancy for men in the United States. Metastatic prostate cancer, the lethal form of the disease, has a life expectancy of approximately five years. Identification of factors associated with this transition to metastatic disease is crucial for future therapies. One such factor is the SSX gene family, a family of cancer/testis antigens (CTA) transcription factors which have been shown to be aberrantly expressed in other cancers and associated with the epithelial to mesenchymal transition (EMT). We have previously shown that SSX expression in prostate cancers was restricted to metastatic tissue and not primary tumors. In this study, we have identified SSX2 as the predominant SSX family member expressed in prostate cancer, and found its expression in the peripheral blood of 19 of 54 (35%) prostate cancer patients, with expression restricted to circulating tumor cells, and in 7 of 15 (47%) metastatic cDNA samples. Further, we examined SSX2 function in prostate cancer through knockdown and overexpression in prostate cancer cell lines. While overexpression had little effect on morphology or gene transcript changes, knockdown of SSX2 resulted in an epithelial morphology, increased cell proliferation, increased expression of genes involved in focal adhesion, decreased anchorage independent growth, increased invasion, and increased tumorigenicity in vivo. We conclude from these findings that SSX2 expression in prostate cancer is not a driver of EMT, but is involved in processes associated with EMT including loss of focal adhesion that may be related to tumor cell dissemination.

A review on Eph/ephrin, angiogenesis and lymphangiogenesis in gastric, colorectal and pancreatic cancers

Erythroprotein-producing human hepatocellular carcinoma receptors (Eph receptors) compose a subfamily of transmembrane protein-tyrosine kinases receptors that takes part in numerous physiological and pathological processes. Eph family receptor-interacting proteins (Ephrins) are ligands for those receptors. Eph/ephrin system is responsible for the cytoskeleton activity, cell adhesion, intercellular connection, cellular shape as well as cell motility. It affects neuron development and functioning, bone and glucose homeostasis, immune system and correct function of enterocytes. Moreover Eph/ephrin system is one of the crucial ones in angiogenesis and lymphangiogenesis. With such a wide range of impact it is clear that disturbed function of this system leads to pathology. Eph/ephrin system is involved in carcinogenesis and cancer progression. Although the idea of participation of ephrin in carcinogenesis is obvious, the exact way remains unclear because of complex bi-directional signaling and cross-talks with other pathways. Further studies are necessary to find a new target for treatment.

Establishment and characterization of a metastasis model of human gastric cancer in nude mice

Background

A mouse model of metastasis of human gastric cancer is one of the most important tools for studying the biological mechanisms underlying human gastric cancer metastasis. In this paper, we established a mouse model of metastatic human gastric cancer in nude mice that has a higher rate of tumor formation and metastasis than existing models.

Methods

To generate the mouse model of metastatic human gastric cancer, fresh tumor tissues from patients that have undergone surgery for gastric cancer were subcutaneously implanted in the right and left groins of nude mice. When the implanted tissue grew to 1 cubic centimeter, the mice were killed, and the tumor tissues were examined and resected. The tumor tissues were implanted into nude mice and subjected to pathological examination, immunohistochemical staining, and real-time PCR for cytokeratin 8/18 (CK8/18), E-cadherin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1). The mice were also analyzed for metastasis in their peritoneum, abdominal cavity, and internal organs by histopathological examination. Tissues collected from these organs were examined for pathology.

Results

After ten generations of implantation, all mice developed tumor growth at the implanted position, 94 % of the mice developed metastasis to the retroperitoneum and viscera. The implanted and metastatic tumor maintained the same histological features across all generations, and metastasis was observed in the esophagus, stomach, spleen, liver, kidney, adrenal, intestine, and pancreas. These metastatic tumors revealed no detectable expression of CK8/18, E-cadherin, VCAM-1, and ICAM-1.

Conclusions

This model will serve as valuable tool for understanding the metastatic process of human gastric cancer.

Aberrant EphB/ephrin-B expression in experimental gastric lesions and tumor cells

AIM: To determine whether the expression profiles of EphB receptor and ephrin-B ligand can be used as markers for dysplastic/oncogenic transformation in gastric mucosa.

METHODS: The protein expression and localization of EphB and ephrin-B in normal, ulcerated regenerating, and dysplastic gastric mucosa were examined in a rat experimental model by immunolabeling, and mRNA expression was assessed in four human gastric carcinoma cell lines by reverse transcription-polymerase chain reaction.

RESULTS: Ephrin-B- and EphB-expressing regions were divided along the pit-gland axis in normal gastric units. EphB2 was transiently upregulated in the experimental ulcer, and its expression domain extended to gastric pits and/or the luminal surface where ephrin-B-expressing pit cells reside. EphB2, B3, and B4 and ephrin-B1 were coexpressed in the experimental gastric dysplasia, and more than one ligand-receptor pair was highly expressed in each of the gastric carcinoma cell lines.

CONCLUSION: Robust and stable coexpression of EphB and ephrin-B is a feature common to experimentally induced gastric dysplasia and human gastric carcinoma cell lines as compared to normal gastric and ulcerated regenerating epithelia. Thus, EphB/ephrin-B may be a useful marker combination for dysplastic/oncogenic transformation in gastric cancer.

EphA3 biology and cancer

Eph receptor tyrosine kinases control cell-cell interactions during normal and oncogenic development, and are implicated in a range of processes including angiogenesis, stem cell maintenance and metastasis. They are thus of great interest as targets for cancer therapy. EphA3, originally isolated from leukemic and melanoma cells, is presently one of the most promising therapeutic targets, with multiple tumor-promoting roles in a variety of cancer types. This review focuses on EphA3, its functions in controlling cellular behavior, both in normal and pathological development, and most particularly in cancer.

Claudin-4 controls the receptor tyrosine kinase EphA2 pro-oncogenic switch through β-catenin

Background

The EphA2 receptor, which is expressed in many types of cancer, is activated by two different mechanisms. Activation by engagement with one of its ephrin ligands is anti-oncogenic whereas phosphorylation of S897 by AKT increases migration, invasion and metastasis. Down-regulation of claudin-4 (CLDN4) produces a loss of E-cadherin and increased β-catenin signaling and a phenotype similar to that produced by oncogenic activation of EphA2, suggesting that CLDN4 may serve to restrain the pro-oncogenic signaling of EphA2.

Results

We found that constitutive knockdown of CLDN4 was associated with a 4.5-fold increase in EphA2 mRNA and a 2.5-fold increase in EphA2 protein which was reversible by re-expression of CLDN4. Knockdown of EphA2 blocked the migratory phenotype induced by loss of CLDN4. Knockdown of CLDN4 resulted in a 5.8-fold increase in pEphA(S897), the oncogenic form of the receptor, as well as partial mislocalization of the excess EphA2 to the interior of the cell. Forced expression of E-cadherin did not reduce total EphA2 or pEphA(S897) whereas re-expression of CLDN4 restored localization and reduced EphA2 and pEphA(S897) even in cells not expressing E-cadherin. Transient siRNA-mediated knockdown of EphA2 and β-catenin, and inhibition of PI3K by LY294002, demonstrated that increased pEphA(S897) in the CLDN4 knockdown cells was attributable to an increase in the level of active dephospho-β-catenin upstream of PI3K and AKT.

Conclusions

We conclude that CLDN4 serves to restrain pro-oncogenic signaling from EphA2 by limiting the activity of β-catenin and PI3K and preventing phosphorylation of EphA2 on S897 by AKT. This suggests that interventions directed at enhancing the level or functional activity of CLDN4 may be of therapeutic interest.

Electronic supplementary material

The online version of this article (doi:10.1186/s12964-014-0059-5) contains supplementary material, which is available to authorized users.

MicroRNA 520d-3p inhibits gastric cancer cell proliferation, migration, and invasion by downregulating EphA2 expression

Aberrant expression of microRNAs (miRNAs) has been shown to play important roles in cancer progression as a result of changes in expression of their target genes. In this study, we investigated the roles of miR-520d-3p on gastric cancer (GC) cell proliferation, migration, and invasion, and confirmed that this miRNA regulates EphA2 expression. The mRNA expression levels of miR-520d-3p and EphA2 in GC tissues and cell lines were evaluated. The clinical and prognostic significance of miR-520d-3p was assessed. The biological function of miR-520d-3p in GC cells was investigated using a methylthiazolyldiphenyl-tetrazolium bromide assay, cell cycle assay, transwell invasion assay, and wound-healing assay. miR-520d-3p expression was down-regulated and inversely correlated with the expression of EphA2 in GC tissues and cell lines. Lower expression of miR-520d-3p was associated with tumor invasion (P = 0.0357), lymph nodes metastasis (P = 0.0272), a higher clinical stage (P = 0.0041), and poorer overall survival (P = 0.0105). Luciferase assays revealed that miR-520d-3p inhibited EphA2 expression by targeting the 3'-untranslated region of EphA2 mRNA. Overexpression of miR-520d-3p dramatically inhibited the proliferation, cell cycle progression, invasion, and migration of GC cells, while down-regulation substantially promoted these properties. Moreover, c-Myc, CyclinD1, and matrix metalloproteinase-9 expression levels were down-regulated in miR-520d-3p mimic-transfected cells and up-regulated in miR-520d-3p inhibitor-transfected cells. Taken together, our data showed that miR-520d-3p appears to contribute to GC progression via the regulation of EphA2 and could serve as a novel prognostic and potential therapeutic marker.

Expression of Eph A4, Eph B2 and Eph B4 receptors in AML

Eph receptors represent the largest subfamily of receptor tyrosine kinases (RTKs). The up- regulation of Eph receptors has been documented in various solid tumors, where it often correlates with poor prognosis. Their significance in hematologic malignancies is still unclear. This study aimed to investigate the expression of Eph A4, Eph B2, and Eph B4 mRNA in non - M3 AML patients and determine their prognostic significance. Bone marrow samples from 101 newly diagnosed non - M3 AML patients and 26 healthy controls for comparison were quantified by real time reverse transcriptase polymerase chain reaction (RT-PCR), and the comparative cycle threshold (Ct) method was used to determine their relative expression levels to GUS control gene. The results showed that expression of all selected Eph receptors was significantly lower in AML patients comparing to controls. It also differed according to FAB subtypes. The decreased expression levels of Eph A4 were associated with higher leukocytes (p = 0.022) and blast cell counts (p = 0.001), and unfavorable FLT3-ITD mutation. Our study revealed significant correlation between lower EphB2 expression levels, and higher complete remission rate (p = 0.009724) and longer overall survival. Additionally, we found that patients with shorter RFS had decreased EphB4 expression (p = 0.00). In conclusion, the results suggest the prognostic impact of decreased expression levels of some Eph receptors in AML patients.

Eph receptors and ephrins as targets for cancer therapy

Eph receptor tyrosine kinases and their ephrin ligands are involved in various signalling pathways and mediate critical steps of a wide variety of physiological and pathological processes. Increasing experimental evidence demonstrates that both Eph receptor and ephrin ligands are overexpressed in a number of human tumours, and are associated with tumour growth, invasiveness and metastasis. In this regard, the Eph/ephrin system provides the foundation for potentially exciting new targets for anticancer therapies for Eph-expressing tumours. The purpose of this review is to outline current advances in the role of Eph receptors and ephrin ligands in cancer, and to discuss novel therapeutic approaches of anticancer therapies.

The role of EPH receptors in cancer-related epithelial-mesenchymal transition

Erythropoietin-producing hepatoma (EPH) receptors are considered the largest family of receptor tyrosine kinases and play key roles in physiological and pathologic processes in development and disease. EPH receptors are often overexpressed in human malignancies and are associated with poor prognosis. However, the functions of EPH receptors in epithelial-mesenchymal transition (EMT) remain largely unknown. This review depicts the relationship between EPH receptors and the EMT marker E-cadherin as well as the crosstalk between EPH receptors and the signaling pathways involved EMT. Further discussion is focused on the clinical significance of EPH receptors as candidates for targeting in cancer therapeutics. Finally, we summarize how targeted inhibition of both EPH receptors and EMT-related signaling pathways represents a novel strategy for cancer treatment.

Ephrin receptor (Eph) -A1, -A2, -A4 and -A7 expression in mobile tongue squamous cell carcinoma: associations with clinicopathological parameters and patients survival

Ephrin receptors (Ephs) are frequently overexpressed in a wide variety of human malignant tumors, being associated with tumor growth, invasion, metastasis and angiogenesis. The present study aimed to evaluate the clinical significance of Eph-A1, -A2, -A4 and -A7 protein expression in mobile tongue squamous cell carcinoma (SCC). Eph-A1, -A2, -A4 and -A7 protein expression was assessed immunohistochemically on 37 mobile tongue SCC tissue samples and was analyzed in relation with clinicopathological characteristics, overall and disease-free patients' survival. All the examined mobile tongue SCC cases were found positive for Eph-A1, -A2, -A4 and -A7. Significant associations were noted between high Eph-A1, -A4 and -A7 expression and absence of lymph node metastases (p = 0.0263, p = 0.0461 and p = 0.0461, respectively). High Eph-A1, -A2 and -A7 expression was significantly more frequently observed in patients presenting absence of vascular invasion (p = 0.0444), dense stromal inflammatory reaction (p = 0.0063) and female gender (p = 0.0327), respectively. Mobile tongue SCC patients with high Eph-A7 expression presented longer overall and disease-free survival compared to those with low Eph-A7 expression (log-rank test, p = 0.0093 and p = 0.0164, respectively). In multivariate analysis, Eph-A7 expression was identified as independent prognostic factor of overall survival (Cox-regression analysis, p = 0.0426). The present study supported evidence that Ephs may participate in the malignant transformation of mobile tongue SCC, reinforcing their utility as clinical markers for patients' management and prognosis, as also as targets for potential therapeutic intervention in tongue chemoprevention.

High levels of EphA3 expression are associated with high invasive capacity and poor overall survival in hepatocellular carcinoma

Although EphA3 expression has been associated with progression or prognosis in several types of tumors, the role of EphA3 in hepatocellular carcinoma (HCC) remains unknown. This study sought to investigate the clinicopathological and prognostic relevance of EphA3 expression in HCC as well as the underlying mechanisms responsible. EphA3 protein was mainly localized within the cytoplasm and at the cell membrane. High EphA3 expression was correlated with tumor size, tumor grade, metastasis, venous invasion and AJCC TNM stage (P<0.05), and patients with high levels of EphA3 expression were at a significantly increased risk for shortened survival time (P<0.05). In vitro, the downregulation of EphA3 expression decreased the invasive capacity of HCC cells via the regulation of VEGF. EphA3 may represent a novel candidate marker for patient prognosis as well a molecular target for HCC therapy.

EphA2 promotes epithelial-mesenchymal transition through the Wnt/β-catenin pathway in gastric cancer cells

This study aims to investigate the significance of erythropoietin-producing hepatocellular (Eph)A2 expression and the mechanism by which EphA2 is involved in the epithelial-mensenchymal transition (EMT) of gastric cancer cells. EphA2 expression levels were upregulated and positively correlated with metastasis and EMT markers in human gastric cancer specimens. Modulation of EphA2 expression levels had distinct effects on cell proliferation, cell cycle, migration, invasion and morphology in the gastric cancer cell lines SGC7901 and AGS in vitro and in vivo. Overexpression of EphA2 resulted in the upregulation of the EMT molecular markers N-cadherin and Snail, as well as the Wnt/β-catenin targets TCF4, Cyclin-D1 and c-Myc, while silencing EphA2 using short hairpin RNA had the opposite effect. Furthermore, inhibition of the Wnt/β-catenin pathway by XAV939 negated the effect of EphA2 overexpression, whereas activation of the Wnt/β-catenin pathway by LiCl impaired the effect of the EphA2 knockdown on EMT. These observations demonstrate that EphA2 upregulation is a common event in gastric cancer specimens that is closely correlated with cancer metastasis and that EphA2 promotes EMT of gastric cancer cells through activation of Wnt/β-catenin signaling.

Clinicopathological significance of platelet-derived growth factor B, platelet-derived growth factor receptor-β, and E-cadherin expression in gastric carcinoma

Aim of the study

Platelet-derived growth factor B (PDGF-B), a vital growth factor which can induce angiogenesis and epithelial-mesenchymal transition (EMT), is important in the metastasis of many tumors. However, the roles of PDGF-B in gastric carcinoma are largely unknown. We investigated the correlation between PDGF-B, PDGFR-β and E-cadherin expression with the clinical features of gastric carcinoma patients to evaluate the relationship between PDGF-B signaling, E-cadherin and metastasis of gastric carcinoma, the correlation between PDGF-B and E-cadherin expression to assess the roles of PDGF-B signaling in metastasis of gastric carcinoma..

Material and methods

We detected expressions of PDGF-B, PDGFR-β and E-cadherin in gastric carcinoma tissues and normal gastric mucosa tissues of 64 patients with gastric carcinoma who had undergone surgical resection, and investigated their relationships with clinical features and the relationships between PDGF-B and E-cadherin expression in gastric carcinoma.

Results

In surgical specimens, tumor cells expressed PDGF-B, and PDGFR-β was expressed by tumor stromal cells. E-cadherin was expressed by both tumor cells and normal gastric mucosa cells. Expressions of PDGF-B and PDGFR-β were increased in gastric carcinoma tissues (p < 0.05) and were positively correlated with the depth of cancer invasion, lymph node metastasis and TNM stage (p < 0.05). The expression of E-cadherin was reduced in gastric carcinoma tissues (p < 0.05) and was negatively correlated with the depth of cancer invasion, lymph node metastasis and TNM stage (p < 0.05). The correlation between PDGF-B and E-cadherin expression was negative (p < 0.05).

Conclusion

Our data indicate that either the overexpression of PDGF-B and PDGFR-β or the underexpression of E-cadherin is correlated with cancer progression and lymphogenous metastasis of gastric carcinoma. The PDGF-B signal pathway might induce EMT by down-regulating expression of E-cadherin to promote metastasis of gastric carcinoma.

Aberrant expression of EphA3 in gastric carcinoma: correlation with tumor angiogenesis and survival

BACKGROUND

EphA3, a member of the Eph receptor tyrosine kinases, plays important roles in tumor angiogenesis and progression. However, the function of EphA3 in solid tumors has not been widely studied. We aimed to explore EphA3 expression in gastric carcinoma and analyze its role as a potential prognostic factor.

METHODS

Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to assess EphA3 mRNA in a normal gastric mucosa cell line and carcinoma cell lines. Immunohistochemistry for EphA3 and vascular endothelial growth factor (VEGF) was performed in 318 cases of gastric carcinoma. CD34 immunohistochemical staining was used for microvessel density (MVD) counting. Western blotting was used to analyze EphA3 expression in the cell lines and to determine the expression of EphA3 and VEGF in 75 cases of gastric carcinoma and matched normal mucosa.

RESULTS

EphA3 mRNA and protein expression was significantly higher in gastric cancer than that in normal mucosa (all P < 0.001). EphA3 was significantly correlated with TNM stage and poor prognosis (all P < 0.001). Multivariate analysis showed that EphA3 had an independent effect on survival (P = 0.037). EphA3 was positively correlated with VEGF (P < 0.001), and MVD (P < 0.001). According to Western blot analysis, both EphA3 and VEGF expression were significantly higher in carcinoma than that in normal mucosa (all P < 0.001). A positive correlation was observed between EphA3 and VEGF expression in cancer (P < 0.001, r = 0.513).

CONCLUSIONS

EphA3 may play important roles in the angiogenesis and prognosis of gastric carcinoma, and thus may become a useful target for therapeutic intervention and a potential indicator for clinical assessment of tumor prognosis.

Immunohistochemical biomarkers in gastric cancer research and management

Gastric cancer still represents a major health problem, despite a decrease in its incidence in the last years. Due to the social impact of gastric cancer (GC), there is a need for novel biomarkers in order to stratify patients into appropriate screening, surveillance, or treatment programs. Although histopathology remains the most reliable and less expensive method, numerous efforts have been made searching for novel biomarkers. In recent years, several molecules have been identified and tested for their clinical relevance in GC management. In this paper, we will focus on a well-known GC marker, whose determination is mandatory in GC, HER2, a marker whose correlation with prognosis is still controversial (VEGF-A) and a quite novel, unconventional marker, the ether-à-go-go-related gene 1 (hERG1). All these proteins can be easily detected with immunohistochemistry, a technique widely used both in diagnostic and research laboratories that represents a link between surgical and molecular pathology, basic science, and clinical medicine.

Eph-dependent cell-cell adhesion and segregation in development and cancer

Numerous studies attest to essential roles for Eph receptors and their ephrin ligands in controlling cell positioning and tissue patterning during normal and oncogenic development. These studies suggest multiple, sometimes contradictory, functions of Eph-ephrin signalling, which under different conditions can promote either spreading and cell-cell adhesion or cytoskeletal collapse, cell rounding, de-adhesion and cell-cell segregation. A principle determinant of the balance between these two opposing responses is the degree of receptor/ligand clustering and activation. This equilibrium is likely altered in cancers and modulated by somatic mutations of key Eph family members that have emerged as candidate cancer markers in recent profiling studies. In addition, cross-talk amongst Ephs and with other signalling pathways significantly modulates cell-cell adhesion, both between and within Eph- and ephrin-expressing cell populations. This review summarises our current understanding of how Eph receptors control cell adhesion and morphology, and presents examples demonstrating the importance of these events in normal development and cancer.

Overexpression of EphA2 correlates with epithelial-mesenchymal transition-related proteins in gastric cancer and their prognostic importance for postoperative patients

The expression of EphA2 and three epithelial-mesenchymal transition-related proteins (E-cadherin, β-catenin and vimentin) was detected by immunohistochemistry in human gastric cancer and normal gastric mucosa. The expression of EphA2 and vimentin was significantly higher in gastric cancer tissues than in normal gastric mucosa tissues, and similar results were found for negative E-cadherin expression and ectopic β-catenin expression. Further analysis showed that the expression of EphA2 was closely correlated with the depth of tumor invasion, tumor-node-metastasis (TNM) stages and lymph node metastasis. Down-regulated expression of the epithelial protein E-cadherin, overexpression of the mesenchymal protein vimentin and ectopic expression of β-catenin were associated with the depth of tumor invasion, tumor differentiation, TNM stages and lymph node metastasis. The Spearman rank test indicated that the positive expression of EphA2 was negatively associated with E-cadherin expression and was positively correlated with β-catenin ectopic expression and vimentin expression. In addition, the Kaplan-Meier survival analysis showed that the overexpression of EphA2 and vimentin, ectopic expression of β-catenin and down-regulation of E-cadherin indicate a poor outcome. Moreover, multivariate Cox analysis showed that TNM stages, lymph node metastasis, EphA2 expression, E-cadherin expression and β-catenin ectopic expression were independent prognostic factors for postoperative gastric cancer. These findings indicate that the overexpression of EphA2 correlates with the loss of epithelial proteins and the appearance of mesenchymal proteins. Therefore, EphA2 may play a role in epithelial-mesenchymal transition in gastric cancer.

Clinical relevance of Ephs and ephrins in cancer: lessons from breast, colorectal, and lung cancer profiling

Pre-clinical studies provide compelling evidence that members of the Eph family of receptor tyrosine kinases and their ephrin ligands promote tumor growth, invasion and metastasis, and neovascularization. Tumor suppressive roles have also been reported for the receptors, and ligand-dependent versus ligand-independent signaling has emerged as one key mechanism underlying tumor suppressive function as opposed to oncogenic effects. Determining how these observations relate to clinical outcome is a crucial step for translating the biological and mechanistic data into new molecularly targeted therapies. Expression profiling in human patient samples bridges this gap and provides valuable clinical relevance to laboratory observations. In addition to analyses performed using privately assembled patient tumor samples, publically available microarray datasets and tissue microarrays linked to clinical data have emerged as tractable tools for addressing the clinical relevance of specific molecules and families of related molecules. This review summarizes the clinical relevance of specific Eph and ephrin molecules in human breast, colorectal, and lung cancers.

Complementary expression and repulsive signaling suggest that EphB receptors and ephrin-B ligands control cell positioning in the gastric epithelium

Eph receptors and ephrin ligands are membrane-bound cell-cell communication molecules with well-defined roles in development. However, their expression and functions in the gastric epithelium are virtually unknown. We detected several EphB receptors and ephrin-Bs in the gastric corpus mucosa of the adult rodent stomach by RT-PCR amplification. Immunostaining showed complementary expression patterns, with EphB receptors preferentially expressed in the deeper regions and ephrin-Bs in the superficial regions of the gastric units. EphB1, EphB2 and EphB3 are expressed in mucous neck, chief and parietal cells, respectively. In contrast, ephrin-B1 is in pit cells and proliferating cells of the isthmus. In a mouse ulcer model, EphB2 expression was upregulated in the regenerating epithelium and expanded into the isthmus. Thus, EphB/ephrin-B signaling likely occurs preferentially in the isthmus, where receptor-ligand overlap is highest. We show that EphB signaling in primary gastric epithelial cells promotes cell retraction and repulsion at least in part through RhoA activation. Based on these findings, we propose that the EphB-positive progeny of gastric stem cells migrates from the isthmus toward the bottom of the gastric glands due to repulsive signals arising from contact with ephrin-Bs, which are preferentially expressed in the more superficial regions of the isthmus and gastric pits.

Eph-A2 and Eph-A4 expression in human benign and malignant thyroid lesions: an immunohistochemical study

BACKGROUND

Ephrin receptors (Ephs) are frequently overexpressed in a wide variety of human malignant tumors, being associated with tumor growth, invasion, metastasis and angiogenesis. The aim of the present study was to evaluate the clinical significance of Eph-A2 and Eph-A4 expression in human benign and malignant thyroid lesions.

MATERIAL/METHODS

Eph-A2 and Eph-A4 protein expression was assessed immunohistochemically on paraffin-embedded thyroid tissues from 131 patients with benign and malignant lesions.

RESULTS

Eph-A2 was significantly overexpressed in malignant compared to benign thyroid lesions (p<0.001). Papillary carcinoma cases presented significantly increased Eph-A2 expression compared to those with hyperplasia nodules (p<0.001). Eph-A4 expression was not differentiated between cases with malignant or benign thyroid lesions. Papillary carcinoma cases presented significantly increased Eph-A4 expression compared to those with hyperplasia nodules (p=0.006). In the subgroup of malignant thyroid lesions, Eph-A2 and Eph-A4 expression was not associated with TNM stage, capsular, lymphatic or vascular invasion.

CONCLUSIONS

The present data suggest that Eph-A2, but not Eph-A4, overexpression may be associated with the malignant transformation of thyroid neoplasia. Further studies conducted on cohorts including a higher proportion of patients with advanced nodal and metastatic disease are recommended to draw definite conclusions on the clinical significance of Eph proteins in thyroid neoplasia.

Global molecular dysfunctions in gastric cancer revealed by an integrated analysis of the phosphoproteome and transcriptome

We integrated LC-MS/MS-based and protein antibody array-based proteomics with genomics approaches to investigate the phosphoproteome and transcriptome of gastric cancer cell lines and endoscopic gastric biopsies from normal subjects and patients with benign gastritis or gastric cancer. More than 3,000 non-redundant phosphorylation sites in over 1,200 proteins were identified in gastric cancer cells. We correlated phosphoproteome data with transcriptome data sets and reported the expression of 41 protein kinases, 5 phosphatases and 65 phosphorylated mitochondrial proteins in gastric cancer cells. Transcriptional expression levels of 190 phosphorylated proteins were >2-fold higher in gastric cancer cells compared to normal stomach tissue. Pathway analysis demonstrated over-presentation of DNA damage response pathway and underscored critical roles of phosphorylated p53 in gastric cancer. This is the first study to comprehensively report the gastric cancer phosphoproteome. Integrative analysis of the phosphoproteome and transcriptome provided an expansive view of molecular signaling pathways in gastric cancer.

Emerging strategies for EphA2 receptor targeting for cancer therapeutics

IMPORTANCE OF THE FIELD

High mortality rates with cancers warrant further development of earlier diagnostics and better treatment strategies. Membrane-bound erythropoietin-producing hepatocellular receptor tyrosine kinase class A2 (EphA2) is overexpressed in breast, prostate, urinary bladder, skin, lung, ovary and brain cancers.

AREAS COVERED IN THIS REVIEW

EphA2 overexpression in cancers, its signaling mechanisms and strategies to target its deregulation.

WHAT THE READER WILL GAIN

High EphA2 expression in cancer cells is correlated with a poor prognosis associated with recurrence due to enhanced metastasis. Interaction of the EphA2 receptor with its ligand (e.g., ephrinA1) triggers events that are deregulated and implicated in carcinogenesis. EphrinA1-independent oncogenic activity and ephrinA1-dependent tumor suppressor roles for EphA2 are described. Molecular interactions of EphA2 with signaling proteins are associated with the modulation of cytoskeleton dynamics, cell adhesion, proliferation, differentiation and metastasis. The deregulated signaling by EphA2 and its involvement in oncogenesis provide multiple avenues for the rational design of intervention approaches.

TAKE HOME MESSAGE

EphA2 has been tested as a drug target using multiple approaches such as agonist antibodies, RNA interference, immunotherapy, virus vector-mediated gene transfer, small-molecule inhibitors and nanoparticles. With over a decade of research, encouraging results with targeting of EphA2 expression in various pre-clinical cancer models necessitate further studies.